An important goal in animal husbandry is to develop biologically active agents which can increase the quantity and improve the quality of meat obtained from livestock animals.
“Increasing the quantity” of food obtained from livestock animals refers to, inter alia, promoting the growth of livestock animals, increasing the efficiency of feed utilized in raising livestock animals and/or enhancing the production of lean body mass in livestock animals. Biologically active agents which cause these effects are, commonly referred to as “anabolic agents”.
“Improving the quality” of food obtained from livestock animals refers to, inter alia, reducing the quantity of subcutaneous fat in meat while at the same time retaining intramuscular fat. Subcutaneous fat, commonly referred to as “trim fat”, can cause elevated cholesterol and/or triglyceride levels in individuals who consume large quantities of meat, has minimal nutritional value, and decreases the overall yield of meat. Therefore, the reduction or elimination of this type of fat from meat is desirable. On the other hand, intramuscular fat, commonly referred to as “marbling”, contributes positively to the flavor of meat and maintains a high Quality Grade. Marbling is a therefore desirable quality. Biologically active agents which are modestly lipolytic can reduce subcutaneous fat while retaining the intramuscular fat.
Certain publications have appeared generally disclosing arylpropanolamines such as U.S. Pat. No. 5,013,761 and WO 97/10825. There is, however, a need for biologically active agents which are both strongly anabolic and modestly lipolytic. Biologically active agents with these properties can be administered to livestock to improve the economics of meat production by increasing the yield of meat (improved Yield Grade). Biologically active agents with these properties can also increase the profitability of meat production by producing meat with a high Quality Grade which, because it is healthier to consume yet retains its flavor, can command high prices from meat packers and consumers.